Light-sheet imaging is rapidly gaining importance for imaging intact biological specimens. Many of the latest innovations rely on the propagation-invariant Bessel or Airy beams to form an extended light sheet to provide high resolution across a large field of view. Shaping light to realize propagation-invariant beams often relies on complex programming of spatial light modulators or specialized, custom made, optical elements.
Light sheet fluorescence microscopy (LSFM) is becoming increasingly important in biological research, in particular for monitoring the development of large three-dimensional samples. Light-sheet microscopy provides high contrast volumetric imaging with minimal sample exposure. The axial resolution of the image is determined by the width of the illuminating light beam. In LSFM, only a thin layer of the sample is illuminated at a time and the images are captured perpendicular to the illuminated plane. Such optical sectioning ability enables high-contrast, high axial resolution, whilst minimizing sample exposure and phototoxicity.
The axial resolution of light sheet microscopy is determined by the combination of the numerical aperture of the detection objective and the thickness of the light sheet. For Gaussian-beam illumination, a large field of view requires a relatively thick light sheet, thus compromising axial resolution or exposing the sample unnecessarily to irradiation. Dual-side illumination or moving the sample along the illumination plane can extend the field of view. However, both methods increase the sample irradiation and may thus induce more photo-bleaching and photo-damage.
High axial resolution has been achieved using extended light sheets by digitally scanning a propagation-invariant Bessel or Airy beam. Airy fields can provide a wide field of view, which is ideal for light-sheet microscopy. The generation of Bessel or Airy light sheets typically require devices for digital scanning and spatial light modulation. This significantly increases the size and complexity of the optical setup. Indeed, practical applications of advanced light-sheet microscopy are often limited by the high cost and complexity of its implementation.